Melting Antarctica could double sea level rise

Unabated greenhouse gas emissions could lead to sea level rise twice as high as we had anticipated, according to a recent study published in Nature.

By the end of this century, scientists predict that sea levels could rise by over 2 meters on average. Note that this is a global average, meaning that some areas could see much higher local rises in sea level. For Small Island Developing States, this could mean the end of their existence altogether. The research has been welcomed by the scientific community, who had already raised reservations with regards to what was called “very conservative” estimates of sea level rise caused by a changing climate.

So what has changed, how could we suddenly double sea level rise? The answer lies in complex processes involved in the melting of ice in Antarctica. Previous estimates had failed to take into account accelerated melting caused by disintegrating ice sheets. In fact, scientists had only been able to consider the melting ice shelves due to increased air and water temperatures, and had ignored the impact of surface melt-water and rainfall which can help fracture large chunks of ice.

The Thwaites glacier is one of the fastest flowing glaciers off Antarctica. Source: Jim Yungel/NASA

Climate change adaptation has been hailed as the ultimate recourse to prevent negative impacts of sea level rise. For instance, in a number of coastal regions, ecosystem-based adaptation helped by mangroves has been underway for some years already. Mangroves play a significant role in protecting coastal regions from intense storms including typhoons, expected to increase in frequency with climate change. Combined with sea level rise, such storm could be catastrophic, especially in densely populated areas.

Mangrove forests like these help protect coastal communities against storms and storm surges.

In previous adaptation planning, the unique property of mangroves to “grow soil” had been counted on to mitigate the impacts of rising sea levels. The rate of growth of mangroves was very much in line with previous climate change projections, yet this new data would suggest that these fragile ecosystems would no longer be able to keep up with the increased rate of sea level rise. Hence, millions of the most vulnerable coastal communities will likely have to rethink their adaptation strategies, a very costly endeavour.

So what is the silver lining? If we achieve the targets set in the 2015 Paris Agreement, sea levels will continue to rise, but never to the rate which would occur if Antarctica’s melting was to start accelerating. Coastal communities will still need to adapt, but costs will be reduced and lives will be saved.